This application is based on and claims priority of Japanese patent application No. 2001-92645, filed on Mar. 28, 2001, the whole contents of which are incorporated herein by reference.
A) Field of the Invention
The present invention relates to a probe unit to be used for a conduction test of an electronic component such as a semiconductor integrated circuit and a liquid crystal panel by making the probe unit in contact with the electrodes or terminal unit of the electronic component.
B) Description of the Related Art
Electronic components such as large scale semiconductor integrated circuits (LSI), liquid crystal panels and printed circuit boards are generally subjected to a conduction test in order to check whether electronic components operate normally in the manner written in the specification. LSI is formed on a silicon substrate. A liquid crystal panel is formed by using a pair of glass substrates. A printed circuit board is formed on a fiber reinforced plastic (FRP) substrate or a polyimide substrate. On these substrates a plurality of electrodes are formed being juxtaposed.
The conduction test is performed by pushing elastic or resilient beams in the front portions of leads of a probe unit against the electrodes on the substrate of an electronic component.
There is a tendency that a pitch of electrodes is becoming finer. A pitch of resilient beams of a probe unit is required to be correspondingly finer.
The pitch of electrodes is presently 0.1 mm or narrower. It is difficult to form a probe unit having such a pitch by a mechanical punching work. Etching or plating has been adopted to form such a probe unit.
For example, JP-A-11-133062 discloses a probe card having leads with contact terminals disposed along the principal surface of the substrate and extending over the edge of the substrate. These leads are coupled to the substrate via a holder unit having a predetermined height. A contact terminal of quadrilateral pyramids is disclosed.
JP-A-8-220140 proposes: a probe card having conductive projections of a pyramid shape having a pointed tip; and a method of manufacturing a probe card by forming a projection by transferring a projection formed by a mold, or fixing a fine conductive wire to a substrate and thereafter cutting the wire.
JP-A-4-363671 proposes a probe board which is manufactured by forming projecting contacts on the end portions of wiring patterns formed on a flexible wiring board, forming resilient members on the bottom surface of the board, and forming slits through the board to separate each of the wiring patterns. The projecting contact has a pointed tip directed toward a contact unit.
JP-A-11-237406 discloses a plated test probe to be made in electrical contact with a solder ball on an integrated circuit device.
JP-A-2-176570 proposes a probe card whose end portions are made in contact with electrodes and has a recess into which the electrodes are inserted.
It is an object of the present invention to provide a probe unit and its manufacture method capable of efficiently inspecting the conduction characteristics of a highly integrated electronic component.
It is another object of the present invention to provide a probe unit and its manufacture method suitable for inspecting parallel wiring lines of an electronic component and capable of dealing with some position misalignment of the probe unit, without damaging the wiring lines during inspection and without damaging probes during manufacture.
According to one aspect of the present invention, there is provided a probe unit comprising: a substrate having an insulated surface; and a plurality of metal leads regularly juxtaposed on the insulated surface of the substrate, the metal lead having a resilient contact piece in a front portion of the lead, the resilient contact piece being spaced apart from the insulated surface or extending over an edge of the substrate, and a vertical cross sectional shape of the resilient contact piece along a longitudinal direction of the metal lead having a portion curved in an arc shape.
According to another aspect of the present invention, there is provided a probe unit comprising: a substrate having an insulated surface; a plurality of metal leads regularly juxtaposed on the insulated surface of the substrate, the metal lead having a resilient contact piece in a front portion of the lead, the resilient contact piece extending over an edge of the substrate; and a projection formed on a surface of the resilient contact piece at a distal end thereof, the projection protruding from the surface of the resilient contact piece toward a direction opposite to the substrate and having a surface shape constituting a portion of a sphere.
According to a further aspect of the present invention, there is provided a probe unit comprising: a substrate having an insulated surface; a plurality of metal leads regularly juxtaposed on the insulated surface of the substrate, the metal lead having a resilient contact piece in a front portion of the lead, the resilient contact piece extending over an edge of the substrate; and a plurality of small projections formed on a surface of the resilient contact piece near at a distal end thereof on a side opposite to the substrate, the small projections having the same shape.
According to a still further aspect of the present invention, there is provided a probe unit comprising: a substrate having an insulated surface; a plurality of metal leads regularly juxtaposed on the insulated surface of the substrate, the metal lead having a resilient contact piece in a front portion of the lead, the resilient contact piece extending over an edge of the substrate; and two projections formed on a surface of the resilient contact piece near at a distal end thereof, in symmetry with a center line of the metal lead along a longitudinal direction thereof, the two projections becoming higher at a position nearer to the edge of the resilient contact piece and having a shape that the projections become higher and skirts of the projections become nearer, from the distal end to a side of the substrate at least up to an intermediate position.
If the resilient contact piece is spaced apart from the substrate, the resilient contact piece can be curved toward the substrate side when the resilient contact piece is pushed against the electrode to be inspected. It is possible to prevent an excessive force from being applied to the electrode, and the electrode is rarely damaged.
If the resilient contact piece is formed curving in an arc shape, stress of the resilient contact piece can be easily controlled.
A plurality of juxtaposed resilient contact pieces can be pushed at the same time against a plurality of electrodes disposed at the end of an electronic component such as an integrated circuit device. This probe unit is suitable for inspecting juxtaposed wiring leads.
An uniform load can be applied to each resilient contact piece at a predetermined bending amount.
A dot can be formed integrally with the resilient contact piece near at its front end portion. It is rare that only the dot is missed.
If the dome-shaped projection is formed at the front portion of the resilient contact piece, the resilient contact piece pushing an electrode hardly damages plated gold or copper wiring leads because the resilient contact piece has no edge.
If a dome-shaped or elongated small dot is formed on both sides of the resilient contact piece, the contact positions of the electrode and resilient contact piece can be automatically corrected from the displaced contact positions.